docs: def gen_table_key(self, table, db='default'):
          """
          Returns a key that is standard for a given table name and database
          alias. Total length up to 212 (max for memcache is 250).
          """
          table = force_text(table)
          db = force_text(settings.DB_CACHE_KEYS[db])
          if len(table) > 100:
              table = table[0:68] + self.gen_key(table[68:])
          if db and len(db) > 100:
              db = db[0:68] + self.gen_key(db[68:])
          return '%s_%s_table_%s' % (self.prefix, db, table)